Covalent inhibition of the SARS-CoV-2 NiRAN domain via an active-site cysteine.

The kinase-like NiRAN domain of nsp12 in SARS-CoV-2 catalyzes the formation of the 5' RNA cap structure. This activity is required for viral replication, offering a new target for the development of antivirals. Here, we develop a high-throughput assay to screen for small molecule inhibitors targeting the SARS-CoV-2 NiRAN domain.